Q: Will taking 5-HTP help me lose weight?
A: Probably not, but it depends. 5-hydroxy-L-tryptophan is a derivative of the amino acid tryptophan and is converted to the neurotransmitter serotonin in the brain. What does that have to do with weight loss? Serotonin is a multifaceted neurotransmitter, and one of its roles is impacting appetite. (Have you ever been in a carb-induced coma where your appetite was completely squashed? Serotonin had a hand in that.)
Because of this connection to hunger, modulating serotonin levels and effects to elicit greater weight loss has long been a pursuit of the drug companies. One of the most famous (or infamous) prescription weight-loss drugs, Phentermine, had a modest impact on serotonin release.
When it comes to actual research on 5-HTP and its impact on weight loss, you won’t find much. In one small study, Italian researchers put a group of obese, hyperphagic (science for “eating too much”) adults on a 1,200-calorie diet and gave half of them 300 milligrams of 5-HTP to take 30 minutes before each meal. After 12 weeks, these participants lost about 7.2 pounds compared to 4 pounds for the rest of the group, who, unknowingly, took a placebo.
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What’s key to note is that while the weight loss for the placebo group wasn’t statistically significant, during the second half of the study, all participants were given specific guidance to reduce their calorie intake. The sugar-pill group missed the calorie mark by almost 800 calories. To me this seems more like not following instructions than the impact of a supplement.
And while it appears the 5-HTP may have helped with weight loss, for someone who is very overweight to lose 7 pounds in 12 weeks while also eating a very calorie-restricted diet isn’t that remarkable.
Outside of this study, there is not a lot more—aside from hypotheses and biochemical mechanisms—to show that 5-HTP is an appetite suppressant. If you are exercising regularly and following a calorie- and carbohydrate-restricted diet plan, then I would have a hard time seeing a benefit to supplementing with 5-HTP.
If you’re still interested in taking 5-HTP, know that it’s readily marketed as seemingly safe and side-effect free, but anyone taking antidepressants, which can unfortunately aid in weight gain, should avoid taking the supplement, as it can mess with the effect and required dose of serotonin in antidepressants.